Quenching and dequenching of octadecyl Rhodamine B chloride fluorescence in Ca2+-induced fusion of phosphatidylserine vesicles: effects of poly(ethylene glycol)

Arnhold, J; Wiegel, D; Hussler, O; Arnold, Klaus

doi:10.1016/0005-2736(94)90189-9

Cited by 7 publications

(9 citation statements)

References 30 publications

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“…Inter-liposomal fusion was monitored by fluorescence increase of octadecyl rhodamine B (R18), which was part of liposome composition. When rhodamine dye molecules are in close proximity to each other, such as in the case of high concentration (7 mol % of R18) in two-dimensional membrane space, the self-quenching occurs [25]. The fluorescence increase is observed when liposomes containing R18 fuse with unlabeled POPC liposomes, which leads to the decrease of effective concentration of R18, that is, an increase of averaged distance between rhodamine dyes.…”

Section: Resultsmentioning

confidence: 99%

pHLIP®-mediated delivery of PEGylated liposomes to cancer cells

Yao

Daniels

Wijesinghe

et al. 2013

Journal of Controlled Release

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We develop a method for pH-dependent fusion between liposomes and cellular membranes using pHLIP® (pH Low Insertion Peptide), which inserts into lipid bilayer of membrane only at low pH. Previously we establish the molecular mechanism of peptide action and show that pHLIP can target acidic diseased tissue. Here we investigate how coating of PEGylated liposomes with pHLIP might affect liposomal uptake by cells. The presence of pHLIP on the surface of PEGylated-liposomes enhanced membrane fusion and lipid exchange in a pH dependent fashion, leading to increase of cellular uptake and payload release, and inhibition of cell proliferation by liposomes containing ceramide. A novel type of pH-sensitive, “fusogenic” pHLIP-liposomes was developed, which could be used to selectively deliver various diagnostic and therapeutic agents to acidic diseased cells.

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Section: Resultsmentioning

confidence: 99%

pHLIP®-mediated delivery of PEGylated liposomes to cancer cells

Yao

Daniels

Wijesinghe

et al. 2013

Journal of Controlled Release

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“…If the liposome were merely to adhere to a target, the donor and acceptor would not disperse and their fluorescence emissions would not change. Fluorescence dequenching is based on similar principles, differing in that a single fluorophore is used which has the ability to quench its own emission when fluorophore molecules are close together (16, 17). As with RET, in true fusion, the fluorophore molecules disperse throughout the target membrane, increasing the spacing between them which increases the light emitted because the self‐quenching is reduced, i.e., fusion allows dequenching.…”

Section: Statement Of Purposementioning

confidence: 99%

Optimizing and quantifying fusion of liposomes to mammalian sperm using resonance energy transfer and flow cytometric methods

Anzar

Kakuda

et al. 2002

Cytometry

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Background Liposomes are used to carry pharmaceutical agents and to alter the lipid composition of cell membranes. This study compared resonance energy transfer (RET), fluorescence dequenching, and flow cytometry as monitors and quantifiers of fusion between liposomes and mammalian spermatozoa. Methods Preliminary experiments used RET to determine the optimum sperm concentration for fusion of DL‐α‐phosphatidylcholine dipalmitoyl (PC)/DL‐α‐phosphatidylethanolamine dipalmitoyl (PE) liposomes at 35°C ± 5 mM Ca2+. Microscopy confirmed the fusion of liposomes, not just adhesion (n = 3). Dequenching tested the time‐dependent fusion of liposomes of two different lipid compositions to sperm, both, (n = 3) ± 1 mM Ca2+ and (n = 3) without Ca2+ at two sperm concentrations. Finally, flow cytometry absolutely quantified the percentage of sperm fusing to liposomes at different liposome‐to‐sperm ratios (n = 4) and with sperm from different donors (n = 3). Results RET detected fusion of liposomes with sperm and microscopy confirmed the interaction to be true fusion. Dequenching detected more fusion of liposomes with sperm at 100 × 106 sperm per milliliter than at lower concentrations (P < 0.05). Fusion dynamics differed with lipid composition but Ca2+ had no effect. Flow cytometry reliably quantified the percentage of sperm fusing with liposomes, which varied from bull to bull (P < 0.05). Conclusion Liposome fusion with mammalian sperm membranes can be quantified cytometrically and varies with lipid composition, sperm‐to‐liposome ratio, and individual animals. Cytometry 49:22–27, 2002. © 2002 Wiley‐Liss, Inc.

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“…Then, for better lipid mixing efficiency and increased delivery of potential liposomeloaded materials, polysaccharide-coated liposomes were used. Fusogenic activities of various water-soluble polymers such as PEG 38 or dextran sulfate 34 have already been reported. As liposomes coated with ChDx behaved like uncoated liposomes in the presence or absence of calcium (Figs.…”

Section: Discussionmentioning

confidence: 99%

Liposomes coated with chemically modified dextran interact with human endothelial cells

Cansell¹,

Parisel²,

Jozefonvicz³

et al. 1999

J. Biomed. Mater. Res.

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Some liposomal formulations are now in clinical use. New applications in biology and medicine using targeted liposomes remain an intensive research area. In this context, liposomes constituted of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cholesterol (70/10/20 mol %) were prepared by detergent dialysis and coated with dextran (Dx) or functionalized dextran (FDx), both hydrophobized by a cholesterol anchor which penetrates the lipid bilayer during the vesicle formation. The coating of liposomes with these polysaccharides was performed because chemically modified dextran but not native Dx interacted with vascular cells. The liposome uptake by human endothelial cells was followed using uncoated and coated liposomes radiolabeled with a neutral lipid ( 3 H-cholesterol) and a polar phospholipid ( 14 C-PC). The results indicated for both radiolabels a preferential uptake by endothelial cells of FDxcoated liposomes compared to uncoated or Dx-coated liposomes. Addition to the culture medium of calcium up to 10 mM further enhanced the level and rate of incorporation of FDx-coated liposomes, whereas interaction of endothelial cells with uncoated liposomes or liposomes coated with Dx was poorly affected. Liposome membranes were then labeled with N-(lissamine rhodamine B sulfonyl)diacyl-PE and liposome uptake by endothelial cells was observed by fluorescence microscopy. The punctate intracellular fluorescence of cells incubated at 37°C with fluorolabeled liposomes is indicative of the liposome localization within the endocytotic pathway of the cells. Altogether, these data demonstrate that coating of liposomes with FDx enable specific interactions with human endothelial cells in culture. Consequently, these liposomes coated with bioactive polymers represent an attractive approach as materials for use as drug delivery vehicles targeting vascular cells.

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Quenching and dequenching of octadecyl Rhodamine B chloride fluorescence in Ca2+-induced fusion of phosphatidylserine vesicles: effects of poly(ethylene glycol)

Cited by 7 publications

References 30 publications

pHLIP®-mediated delivery of PEGylated liposomes to cancer cells

pHLIP®-mediated delivery of PEGylated liposomes to cancer cells

Optimizing and quantifying fusion of liposomes to mammalian sperm using resonance energy transfer and flow cytometric methods

Liposomes coated with chemically modified dextran interact with human endothelial cells

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